package cn.sinata.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Base64DES {
	
	private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();

	public static String encode(byte[] data) {

		int start = 0;
		int len = data.length;
		StringBuffer buf = new StringBuffer(data.length * 3 / 2);
		int end = len - 3;
		int i = start;
		int n = 0;
		while (i <= end) {
			int d = ((((int) data[i]) & 0x0ff) << 16)
				| ((((int) data[i + 1]) & 0x0ff) << 8)
				| (((int) data[i + 2]) & 0x0ff);

			buf.append(legalChars[(d >> 18) & 63]);
			buf.append(legalChars[(d >> 12) & 63]);
			buf.append(legalChars[(d >> 6) & 63]);
			buf.append(legalChars[d & 63]);
			i += 3;
			if (n++ >= 14) {
				n = 0;
				buf.append(" ");
			}
		}
		if (i == start + len - 2) {
			int d = ((((int) data[i]) & 0x0ff) << 16)
				| ((((int) data[i + 1]) & 255) << 8);

			buf.append(legalChars[(d >> 18) & 63]);
			buf.append(legalChars[(d >> 12) & 63]);
			buf.append(legalChars[(d >> 6) & 63]);
			buf.append("=");

		} else if (i == start + len - 1) {
			int d = (((int) data[i]) & 0x0ff) << 16;
			buf.append(legalChars[(d >> 18) & 63]);
			buf.append(legalChars[(d >> 12) & 63]);
			buf.append("==");
		}
		return buf.toString();
	 }
	
	public static byte[] decode(String s) {

		ByteArrayOutputStream bos = new ByteArrayOutputStream();

		try {

			decode(s, bos);

		} catch (IOException e) {

			throw new RuntimeException();

		} catch (Exception e){
			e.printStackTrace();
		}

		byte[] decodedBytes = bos.toByteArray();

		try {

			bos.close();

			bos = null;

		} catch (IOException ex) {

//			System.err.println("Error while decoding BASE64: " + ex.toString());

		}

		return decodedBytes;

		}

		private static void decode(String s, OutputStream os) throws IOException {

			int i = 0;

			int len = s.length();

			while (true) {

				while (i < len && s.charAt(i) <= ' ')

					i++;
					if (i == len)
						break;

						int tri = (decode(s.charAt(i)) << 18)
								+ (decode(s.charAt(i + 1)) << 12)

								+ (decode(s.charAt(i + 2)) << 6)

								+ (decode(s.charAt(i + 3)));

						os.write((tri >> 16) & 255);

					if (s.charAt(i + 2) == '=')

						break;

						os.write((tri >> 8) & 255);

					if (s.charAt(i + 3) == '=')

						break;
						os.write(tri & 255);
						i += 4;
					}
		}

		private static int decode(char c) {

			if (c >= 'A' && c <= 'Z')

				return ((int) c) - 65;

			else if (c >= 'a' && c <= 'z')

				return ((int) c) - 97 + 26;

			else if (c >= '0' && c <= '9')

				return ((int) c) - 48 + 26 + 26;

			else

				switch (c) {

				case '+':

					return 62;

				case '/':

					return 63;

				case '=':

					return 0;

				default:

			throw new RuntimeException("unexpected code: " + c);

		}

	}
}
